Portable radio communication devices are widely used to facilitate communication among individuals and within organizations. Cellular phones, for example, are nearly ubiquitous in metropolitan regions around the world. These devices have become so popular that their design is influencing design approaches for other types of portable radio communication devices. One aspect of current cellular phone design that has become standard is the lack of an external antenna. Internal or hidden antennas are instead used for the various transceivers and receivers included in a typical “smart” phone device, and this is a feature that consumers have come to associate with a modern communication device.
Portable two-way radio devices, another type of portable radio communication device, are used to facilitate two-way (i.e. half duplex) radio communication with near instant communication access. These devices typically have a “push to talk” operation which allows a user to commence talking, and to be heard by others, at the push of a button. When a two-way radio device receives a signal on a monitored channel it can simply play received audio/voice signals over a loudspeaker, or a headset/earpiece at virtually the same time as it is being transmitted by the speaker's two-way radio device. Since two-way radio communication avoids delays present in cellular communication, it has persisted as a communication modality preferred by organizations such as police, fire/rescue, military, and other organizations where near-instant communication is essential.
The adoption of internal antennas in cellular phones, however, has been, in part, facilitated by the evolution of cellular protocols to higher frequencies. Conversely, standardized two-way radio communication is still conducted in Very High Frequency (VHF) bands, which is a much lower frequency than is used in cellular telephony communication. Since antenna size is inversely related to frequency, it has not been practical to adopt antenna designs used in cellular communication into two-way radio communication devices. However, eliminating, or substantially eliminating the conventional external antenna in two-way radio communication devices would be attractive to users of such devices for a number of reasons, including that it would make such devices easier to carry.
Accordingly, there is a need for an antenna structure that can be used in portable two-way radio devices that substantially eliminates or minimizes the need for an external antenna.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.